Figure 1.

Age distributions of LTR-retrotransposon superfamilies. Athila insertions are on average significantly older, and Copia-like ones younger, than those from other superfamilies. There are 34 Copia-like, four Athila, and three Gypsy-like insertions with identical intra-element LTRs. The width of the horizontal boxes above the histograms indicates the middle 50% of age values in each superfamily; the red band indicates 95% confidence limits on the median, and the green stripe the median value.